Ambulatory infusion devices for the infusion of a liquid drug over an extended time period are used for a number of therapies. In particular, such devices form the basis for a state-of-the-art therapy of Diabetes Mellitus by CSII (Continuous Subcutaneous Insulin Infusion). Besides diabetes therapy, those devices may be used for a number of further therapies, such as cancer treatment or pain therapy, without requiring substantial modification. The following description mainly refers to CSII therapy by insulin infusion without being limiting to this specific application.
While present ambulatory infusion devices may be comparably comfortable, easy to use and robust, a number of malfunctions and error situations are known to occasionally occur, partly resulting from device defectives, and partly from handling errors. Those situations are, among others, leakages of the drug reservoir or the infusion tubing, occlusions, and a flow-back of administered insulin along the cannula and out of the subcutaneous tissue. While some of these conditions, in particular occlusions, may typically be detected by pre-sent ambulatory infusion devices with a generally undesired delay, some others, such as leakages or a drug flow-back, may not be detected at all by current devices. All of such events are in the following referred to as “administration anomalies”.